Hydrochloric Acid → methyl 1-amino-3-chloro-1H-pyrrole-2-carboxylate hydrochloride

A mixture of sodium hydride (60%, 0.8 g, 20 mmol) and methyl 3-chloro-1H-pyrrole-2-carboxylate (Tetrahedron, 1999, 55, 4133–4152; 2.5 g, 15.7 mmol) in DMF (10 mL) at 0° C. was stirred for 25 min, then was added 2,4-dinitrophenolamine (Tetrahedron Lett. 1968, 16, 1909–1910 and J. Heterocyclic Chem. 1967, 413, 3.80 g, 19.1 mmol) and the reaction mixture was stirred at 0–5° C. for 2.5 h. The mixture was diluted with 10% aqueous LiCl solution and the product was extracted with EtOAc (3×100 mL). The EtOAc solution was washed with 10% LiCl solution (2×80 mL), brine (80 mL), dried over MgSO4 and concentrated in vacuo to give the crude product as a brown oil. The crude product was treated with 4 N HCl in dioxane (2 mL) in Et2O (60 mL). The precipitated solid was collected, washed with Et2O and dried in vacuo to obtain the title compound (3.30 g, 99%): 1H NMR (DMSO-d6) δ 7.17 (d, 1H, J=2.2 Hz), 6.68 (d, 1H, J=2.2 Hz), 3.74 (s, 3H).

1. stirringthe reaction mixture was stirred at 0–5° C. for 2.5 h
2. extractionthe product was extracted with EtOAc (3×100 mL)
3. washThe EtOAc solution was washed with 10% LiCl solution (2×80 mL), brine (80 mL)
4. dry with materialdried over MgSO4
5. concentrationconcentrated in vacuo
6. customto give the crude product as a brown oil
7. customThe precipitated solid was collected
8. washwashed with Et2O
9. customdried in vacuo

ORD record

ord-d52e4c616db447058f6640dc3a1198f3

Source dataset

uspto-grants-2006_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07030118B2